code: def test_min_train_series_length_without_seasonality(self):
      fourtheta = FourTheta(
          model_mode=ModelMode.MULTIPLICATIVE,
          trend_mode=TrendMode.EXPONENTIAL,
          season_mode=SeasonalityMode.ADDITIVE,
          seasonality_period=None,
          normalization=False,
      )
      theta = Theta(
          season_mode=SeasonalityMode.ADDITIVE,
          seasonality_period=None,
      )
      assert fourtheta.min_train_series_length == 3
      assert theta.min_train_series_length == 3
  
file_path: darts/darts/tests/models/forecasting/test_4theta.py
imports: import random
  import numpy
  import pytest
  from darts.metrics import mape
  from darts.models import FourTheta, Theta
  from darts.utils.timeseries_generation import linear_timeseries
  from darts.utils.timeseries_generation import random_walk_timeseries
  from darts.utils.timeseries_generation import sine_timeseries
  from darts.utils.utils import ModelMode, SeasonalityMode, TrendMode
label_desc: Use image node_id 7 for calling the TestFourTheta obj's underlying member method code with example usage: obj.test_min_train_series_length_without_seasonality() without return types